Belt-type sanders are old and well known in the art. They have an extended belt bed with an idler pulley at one end and a driven pulley at the other. An adjustment mechanism moves the idler pulley in sufficiently far to allow an endless belt having an emery-type surface for sanding purposes to be placed thereon. The idler pulley is then adjusted outwardly until the belt is tight about the drive pulley and the idler pulley. The belt bed allows a workpiece to be sanded to be placed on the bed while the belt is being driven and thus the workpiece is sanded.
As can be imagined, the sanding operation generates a considerable amount of dust. In the prior art, a dust collector is placed around the driving pulley to encircle the end of the belt carrying the dust toward the dust collector. A vacuum of any known type may be coupled to an orifice on the dust collector and the dust removed by the vacuum as it enters the dust collector.
An end stop is generally placed in front of the dust collector and just above the surface of the belt. The end stop allows the work piece to rest against it for supporting the work piece while it is being sanded. It is raised a small distance above the belt so that the dust being generated can be carried by the belt into the dust collector.
Further, the belt table has the ability to move from its horizontal position to a vertical position for facilitating certain types of sanding. Typically, when the belt is in its horizontal position, it is held rigidly by two bolts that pass through the frame into the belt bed. Therefore, in order to tip the bed upwardly 90.degree., the two bolts must be removed, the belt tilted 90.degree. and the bolts reinserted into the frame and the belt bed. Clearly this is time-consuming and an inconvenience to the user of the sander. In addition, one should know reasonably accurately when the belt is in its vertical and horizontal positions. The ability to place the bed in either the horizontal or vertical planes in an accurate manner should be done in a manner that is relatively quick and easy for the user of the machine.
The present invention overcomes the disadvantages of the prior art by providing a belt sander which has a single set screw or bolt to lock the belt bed to the frame in any desired position. This is accomplished by having a C-shaped collar forming a portion of the frame. A circular support structure, such as a wheel-like device with a wide surface on the periphery thereof, is attached to the belt bed and positioned within the C-shaped collar that forms a portion of the frame. The circular support structure rides within the C-shaped collar and enables the belt bed to be selectively rotated 90.degree. from a horizontal position to the vertical position. By loosening the set screw or bolt on the C-shaped collar, pressure is relieved about the circular support means to allow the belt bed to pivot. However, when the set screw is tightened, the ends of the C-shaped collar move toward each other and clamp about the circular support means to prevent the belt bed from rotating. The C-shaped clamp has a flat inner surface and the flat outer surface of the circular support structure is placed in mating contact with the flat inner surface of the C-shaped collar so that as the C-shaped collar is tightened by the set screw, it will grip the flat outer surface of the circular support structure and hold it in fixed relationship. A recess is formed in each outer end of the C-shaped collar. An orifice in one recess extends in alignment to an orifice in the other recess and the set screw or bolt is inserted in the aligned orifices which, when tightened, pulls the ends of the C-shaped collar together and clamps it about the circular support structure to lock the bed in the selected position.
A bed position indexing pin extends outwardly from the C-shaped collar. A device is associated with the circular support structure on the bed for engaging the pin at 0.degree. and 90.degree. to position the belt bed with a positive stop at the 0.degree. and 90.degree. positions. The device is an annular fixture that extends through the C-shaped collar. A first inwardly-extending flange on a first end of the annular fixture is on the inside of the C-shaped collar for attachment to the circular support structure rigidly mounted to the belt bed. A second outwardly-extending flange on the other end of the annular fixture is on the outside of the C-shaped collar and rotates with the belt bed when it is moved from the 0.degree. to the 90.degree. position. An arcuate recess is formed in the second flange for receiving the indexing pin. It has a first shoulder for engaging the indexing pin at a 0.degree. horizontal belt bed position and a second shoulder for engaging the indexing pin at a 90.degree. vertical belt bed position so as to provide automatic stops at the correct 0.degree. and 90.degree. belt bed positions.
Thus it is an object of the present invention to provide a belt-type sander which has a bed that can be moved from the horizontal position (0.degree.) to a vertical position (90.degree.) and which has a single bolt or set screw that can be loosened to move the bed to the desired position and then tightened to lock the bed into position.
It is also an object of the .present invention to provide an indexing pin on the frame that engages an arcuate slot in a flange attached to the belt bed such that in a first position, a first shoulder in the recess engages the indexing pin at the 0.degree. position and a second shoulder in the recess engages the indexing pin at the 90.degree. position, thus providing positive stops and accurately positioning the belt bed at the 0.degree. and 90.degree. positions.